Enter this guide by [Mithuna] from Looking Glass Universe, where she circles back on the concept of measurement basis in quantum mechanics using a rather simple piece of calcite crystal.

Found all over the world, calcite is the most stable form of calcium carbonate and is the main mineral found in limestone. We find calcite in the ocean, in shells or hard parts of marine organisms ...

CALCIUM carbonate can exist in three polymorphic forms, which in the order of their usual stabilities are calcite, aragonite and vaterite. Calcite is the most stable and the least soluble ...